How many tunnels are there?
Tunnels are counted nationally and not globally, and the national figures are wildly unequal. China has roughly 25,000 road tunnels totalling around 27,000 km, the overwhelming majority built since 2000. Norway, with a population of 5.5 million, has about 1,200 road tunnels because its geography leaves no alternative. The United States, far larger than both, has only around 500 highway tunnels in its federal inventory, because American road building historically preferred to go around or over.
How the figure is arrived at
National transport ministry asset registers, which exist because tunnels require fire safety systems, ventilation and inspection regimes and therefore have to be enumerated. Comparing countries is treacherous: definitions differ on minimum length, and whether metro, rail and utility tunnels are included changes totals by an order of magnitude.
How confident it is
- Low estimate
- 20,000
- High estimate
- 30,000
- Spread
- 1.5× between the bounds
Other things people built counts
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many books have ever been published? about 130 million as of 2010 — probably over 200 million now
- How many airports are there in the world? about 45,000 with runways — but only around 4,000 with scheduled airline service
- How many ATMs are there in the world? about 3 million
- How many cities are there in the world? about 10,000 with over 50,000 people; 33 megacities over 10 million
- How many buildings are there in the world? somewhere between 1.5 and 4 billion
- How many computers are there in the world? roughly 2 billion personal computers in use
Common questions
- How many tunnels are there?
- no global count — China alone has about 25,000 road tunnels
- How is that estimated?
- National transport ministry asset registers, which exist because tunnels require fire safety systems, ventilation and inspection regimes and therefore have to be enumerated. Comparing countries is treacherous: definitions differ on minimum length, and whether metro, rail and utility tunnels are included changes totals by an order of magnitude.
Related pages
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many people are there in the world? Living things and the natural world
- How many stars are there in the universe? Space and the universe
- How many bones are in the human body? The human body
- How many grains of sand are there on Earth? Living things and the natural world
- How many ants are there in the world? Living things and the natural world
- How many trees are there in the world? Living things and the natural world
Sources
- Typical range compiled from manufacturer specifications — At One Place